Orthogonal frequency division multiplexing (OFDM) is a form of multiplexing that distributes data over a number of carriers that have a very precise spacing in the frequency domain. The precise spacing of the carriers provides several benefits such as high spectral efficiency, resiliency to radio frequency interference and lower multi-path distortion. Due to its beneficial properties and superior performance in multi-path fading wireless channels, OFDM has been identified as a useful technique in the area of high data-rate wireless communication, for example wireless metropolitan area networks (MAN). Wireless MAN are networks to be implemented over an air interface for fixed, portable, and mobile broadband access systems. A standard being developed for use with OFDM and wireless networks is IEEE 802.16.
In early versions of the standard for IEEE 802.16 there was no accepted manner for hybrid automatic repeat request (H-ARQ) operation. The accepted down-link (DL) and up-link (UL) allocation mapping (or MAP) information element (IE) structure had no IE formats that enabled H-ARQ communication between devices.
Also, in more recent versions of the IEEE 802.16 standard, a bandwidth (BW) request media access control (MAC) header is used for a registered wireless terminal to request UL bandwidth. However, there is no authentication field attached to this header. As no formal registration to a network is needed to request resources from the network, any malicious terminal can monitor a UL-MAP message sent by a base station and determine an OFDM region assigned for sending a BW request code (taking OFDMA PHY as an example) and then sending the BW request header using a CID (connection identification) assigned to a wireless terminal that is registered with the network. Such a malicious wireless terminal may significantly interfere with normal operation of a network operating in compliance with the IEEE 802.16 standard.
A need exists for improved systems and methods to overcome these problems.